摘要
在简阳地区的TF-2井,上二叠统龙潭组发育凝灰岩,其储层物性良好,但目前对凝灰岩成因以及孔隙演化过程尚不清楚,影响着对该层油气潜力的评价。本次研究对研究区龙潭组中上部两件有代表性的凝灰岩样品开展了详细宏观观察、薄片鉴定、扫描电镜分析、地球化学数据等综合研究,从而厘清了研究区凝灰岩物质来源,并分析孔隙演化过程。两件凝灰岩样品为岩屑凝灰岩,发生强烈蚀变,X衍射结果显示主要由黏土矿物组成;能谱分析和扫描电镜结果显示储集孔隙类型主要为脱玻化孔和长石的溶蚀孔;地化数据显示样品TiO_(2)含量较高、Al_(2)O_(3)/TiO_(2)比值较低、明显的Eu负异常、微量元素(Cr,V,Cu,Ti)的含量较高等特征。结合前人研究数据,认为四川盆地西南部龙潭组凝灰岩物质来源于峨眉山高钛玄武岩,其孔隙演化过程为火山玻璃脱玻化形成微孔隙,其次,钠长石溶蚀形成高岭石和石英,再次,高岭石转化成绿泥石,最后,保留部分原生孔和长石溶孔、黏土矿物晶间孔等次生孔隙。
The tuff developed in the Upper Permian Longtan Formation in Well TF-2, Jianyang area shows good reservoir properties. However, the hydrocarbon potential of the tuff reservoir is affected by the unknown tuff genesis and pore evolution. In this paper, two representative tuff samples were collected from the middle and upper part of Longtan Formation were studied by detailed macroscopic observation, thin section identification, SEM analysis and comprehensive analysis of geochemical data, thus clarifying the material source of tuff in the study area and analyzing the pore evolution process. The two tuff samples are lithic tuff, strongly altered, with X-ray diffraction analysis showing that the rocks are mainly composed of clay minerals. The results of energy spectrum and scanning electron microscope analysis show that the reservoir pore types are mainly devitrification pores and feldspar dissolution pores. Geochemical analysis shows that the tuff samples have high TiOcontent, low Al_(2)O_(3)/TiO_(2)ratio, and high trace elements(Cr, V, Cu, Ti) content with obvious negative Eu anomaly. According to the research results of this study, combined with previous research data, it is considered that the Longtan Formation tuff in the southwest Sichuan Basin is derived from the high titanium basalt of Emeishan Mountain. The pore evolution of tuff is mainly characterized by the the formation of micropores resulted from devitrification of volcanic glass. Secondly, the albite in the rocks is dissolved to form kaolinite and quartz, and then some kaolinite are transformed into chlorite. Finally, some primary pores together with such secondary pores as solution pores of feldspar and intergranular pores of clay minerals are preserved in the rocks.
作者
曹佳佳
张玺华
龚婷婷
黄一钒
林郑旸
骆昊天
陈延贵
杨帅
CAO Jiajia;ZHANG Xihua;GONG Tingting;HUANG Yifan;LIN Zhengyang;LUO Haotian;CHENYangui;YANG Shuai(l.instituteof sedimentary geology,chengdu university of technology,chengdu,sichuan 610059,china;erploration and development research institute,petrochina southwest oil&gasfield com pany,chengdu,sichuan 61004l,china;college of earthscience,chengdu university of technology,chengdu,sichuan 610059,china)
出处
《矿物岩石》
CAS
CSCD
北大核心
2022年第4期94-103,共10页
Mineralogy and Petrology
基金
国家自然科学基金面上项目(批准号:42172132)
成都理工大学珠峰科学研究计划项目(编号:2022ZF11402)。
